(1) Field of the Invention:
The present invention relates to a fabric structure for fiber reinforced plastics (hereinafter referred to as FRP). More particularly, the invention relates to a fabric structure which is valuable as a reinforcing material for FRP, especially for a resin to be used as a matrix in FRP.
(2) Description of the Prior Art:
FRP formed of a resin reinforced by a fibrous material composed of reinforcing fibers such as carbon fibers or glass fibers is well known. A woven fabric of reinforcing fibers is often used as the fibrous material.
In a fibrous material in the form of a woven fabric, however, since reinforcing fibers are bent at crossing points of warps and wefts, the stress is concentrated on those bent portions and therefore, characteristic properties of reinforcing fibers, such as high tenacity and high elasticity, cannot be sufficiently utilized.
Furthermore, when FRP having a cone-like or dome-like shell structure, such as an acoustic vibratory plate for a loud speaker, is formed by using one sheet of a woven fabric, since the reinforcing fibers come to have a shape resembling a bent corrugated sheet, the flexural stiffness is not sufficiently manifested.
Attempts have heretofore been made to form FRP by using a so-called unidirectional woven fabric composed of warps consisting of straight reinforcing fibers free of bends.
However, in the unidirectional woven fabric, since physical properties in the warp direction differ from those in the weft direction and the woven fabric is anisotropic in physical properties, warps should be arranged so that groups consisting of a plurality of warps are laminated to cross one another, and therefore, the operation of forming FRP becomes complicated and troublesome.